APEX is dedicated to the development and test of a new concept high-repetition rate high-brightness electron injector optimized to operate at the performance required by a high-repetition-rate x-ray FEL. The baseline for the injector design for LCLS-II is the VHF gun of APEX. LBNL is responsible for the design, construction and commissioning of the injector.
The successful development of such an injector will dramatically impact not only the performance of future 4th generation light sources when high repetition rates (> 10 kHz) are required, but also high-repetition-rate ultrafast electron diffraction (UED) and microscopy, as well as inverse Compton scattering (ICS) applications. ATG has designed and deployed the LLRF system for the APEX injector and accelerating section.
The Advanced Light Source (ALS) Instrumentation and Controls Upgrade is an approximately $8M/4-year project involving the development and replacement of critical parts of the accelerator. ATG has contributed to the upgrade providing engineering knowledge and skill in the accelerator controls software and EPICS side, Beam Position Monitors (BPMs), timing and synchronization and system integration.
The timing system at ALS had not been replaced since the construction of the machine at the beginning of the 1990s. While reliable, it has raised concerns over the years due to the limits of scaling to serve a larger amount of equipment, and the limited knowledge of its internal operation by current ALS staff. Carlos Serrano of ATG contributed, in collaboration with the ALS Engineering staff, to a full study of the existing system providing insight on its interconnections, internal functions and limitations, and worked on the proposal, planning, prototyping and deployment of an FPGA-based solution using commercially available hardware, benefiting from 20 years of improvements in the fields of digital electronics and optical communications.
Project:
ALS Controls Upgrade
Date:
2011-2015
Contribution:
BPMs & Timing System
LZ Dark Matter Experiment
The LUX-Zeplin (LZ) collaboration is designing a next generation dark matter detector with unprecedented sensitivity to detect weakly interacting massive particles (WIMPs). The detector is a two-phase xenon design which uses approximately 7 metric tons of xenon.
Members of the Advanced Technologies Group are developing the high voltage structures that make up the time projection chamber of the detector.
In collaboration with the Earth Sciences Division at LBNL, ATG developed the Berkeley Unexploded ordnance Discriminator (BUD). The application of this device originated in the need to clean up 15 million acres of US territory, previously used by the military, considered to potentially contain unexploded ordinance (UXO). Traditional metal detectors were incapable of differentiating metal scrap from UXOs, the former accounting for up to 90% of metal encountered in these sites, favoring a technology that would limit the amount of digging in order to clean and release the land back to the public.
The novelty of this device is the ability to report the following information related to the buried objects:
Size,
Location,
Orientation,
Material.
The way BUD detects and characterizes metallic objects is by generating a large electromagnetic pulse on a driver coil, inducing currents in the metallic objects, and measuring the response of these objects by very sensitive receiver coils connected to ultra low-noise electronics.
ATG designed both the high-voltage analog board to drive the transmitter coils, along with the the low-noise digitizer board to acquire the receiver signals. Some of the design challenges include the need to shut off the current in the transmitter coil very rapidly and the ability to operate the digitizers over a very large dynamic range (more than 160 dB). The excitation signal induces around 100 V in the receiver coils, which needs to decay and detect signals from the objects in the nV range a few milliseconds after transmitter shut-off. Due to the low amplitude of the signals of interest, good noise performance in the electronics is fundamental. Power consumption is another important element since the device is portable and battery operated.
The first version of the receiver data acquisition board is shown below. It features:
Xilinx Spartan 3 FPGA,
USB port,
12 channels,
16-bit, 250 kS/s ADCs.
The picture below shows the 3-channel transmitter switching pulser board, rated for 300V, 20A, which is connected to a capacitor bank and an inductive load. Timing is controlled from the FPGA board to synchronize the excitation pulses and the data acquisition.
ATG members have been involved in the design, development and operations of BUD since 2004 and continue to collaborate with the Earth Sciences Division for further development and improvements, both on the sensor side, electronics and software. Our main contributions include:
Full design of the transmitter pulser board and the data acquisition board,
FPGA firmware design,
Full software stack for data transfer from the digitizers to high-level software,
User interface design,
Complete modeling and system characterization of both the sensors and the electronics using SPICE,
Prototype design and production.
We have also been involved in the different surveys dedicated to evaluate the performance of the various UXO detectors developed nation-wide, where BUD has always showed excellent results. The picture below shows one of the first prototypes being evaluated in a site in San Luis Obispo, CA, in July 2009.
Below is the latest version of BUD, where both size and weight have been reduced dramatically along with better performance on the receiver coil, load termination circuitry and operations software, where the device is capable of characterizing the objects live without the need of offline data processing. The picture corresponds to a survey that took place in Spencer, TN, in June 2012.
Contribution:
Data Acquisition and High-Power Electronics
NCDX-II
The Neutralized Drift Compression Experiment (NDCX-II) is an induction accelerator facility at LBNL which is designed to study intense beam physics and to pulse-heat target materials to investigate defect dynamics and high energy density physics. An ion beam is compressed both radially and longitudinally in the presence of plasma to neutralize the beam space charge and maximize the peak energy on the target.
Members of the Advanced Technologies Group designed and implemented the accelerator high voltage designs, pulsed power systems, and control systems.
References:
W.L. Waldron, et al., “The NDCX-II Engineering Design”, Nuclear Instruments and Methods in Physics Research A, 733 (2014).
ALS-U is the upgrade of the Advanced Light Source at LBNL to a diffraction limited storage ring for increased brightness.
Members of the Advanced Technologies Group are developing fast kicker magnets and pulsers required to transfer the beam between the accumulator ring and the storage ring.
